1. Field of the Invention
The present invention relates to improvement in timer start control under an unmanned state in an on-vehicle electronic control device and, more specifically, to an on-vehicle electronic control device designed to achieve a higher reliability so as to prevent the start due to malfunction.
2. Description of the Related Art
An on-vehicle electronic control device that is constituted of a main control circuit section provided with a microprocessor acting as a main CPU and a timer circuit section is well known.
For example, the Japanese Patent Publication (unexamined) No. 315474/2003 titled “Electronic Control Device and Semiconductor Integrated Circuit” proposes a concept, in which as to a soak timer for detecting a left-time period relative to a preheating control of a coolant, a transpiration detection of fuel or the like, a soak timer covering a wide variety of applications is disclosed to measure a left-time period with a measurement time and a measurement accuracy in compliance with usage.
As a prior art relevant to this invention, the Japanese Patent Publication (unexamined) No. 18315/1993 titled “Automobile Engine Control Device” proposes another concept, in which in a central processing unit (CPU) that is fed with an electric power via an output contact and a power supply circuit of a power supply relay operating when a power supply switch is closed from an on-vehicle battery, the operation of a power supply relay is held when a pulse signal to be generated at the time of normal operation of a CPU, and the CPU executes various initialization processing, and then stops the generation of pulses after the power supply switch is brought in an open circuit thereby performing the de-energization of the power supply relay.
The Japanese Patent Publication (unexamined) No. 197853/1992 titled “Vehicle Theft-Proof Device” proposes a further concept, in which a monitor light-emitting device is brought in flashing, and a flashing cycle thereof is made to be longer as an elapsed time period increases from the start of alerting.
In the above-mentioned electronic control device according to the Japanese Patent Publication (unexamined) No. 315474/ 2003, a power supply relay is energized with an OR output of output signals from the power supply switch and the soak timer to feed an electric power to the on-vehicle electronic control device. Accordingly, in the case where a power supply relay remains to be switched on due to, e.g., malfunction of the soak timer and the on-vehicle electronic control device is fed with an electric power over a long time period in an unmanned state, an over-discharge of an on-vehicle battery is induced.
Moreover, there is a high risk of on-vehicle current consumers being improperly fed with an electric power in the state that an engine is stopped to induce a burning accident. The above-mentioned electronic control device is of a circuit arrangement unprotected against an unmanned power feed.